Press construction



INVENTOR. far/ A. Bis/'5' ATTORNEY 3 Sheets-Sheet 1 C A RIETZ PRESSCONSTRUCTION -l m-Hrudw R Sept. 9, 1952 Filed Sept 30, 1946 Sept. 9,1952 Filed Sept. 30, 1946 FJLIE ZE 3 Sheets-Sheet 2 w W i i\ l 1 m I R Rv INVENTOR car/Amer;

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' ATTORNEY Patented Sept. 9, 1952 UNITED STATES ATENT OFFICE PRESSCONSTRUCTION Application September 30, 1946, Serial No. 700,228

2 Claims. (01. 100-148) This invention relates generally to pressconstructions of the screw type adapted to express water or other liquidfrom a feed material.

Conventional presses of the screw type make use of a cylindrical screensurrounding a suitable screw and having its one end arranged to receivefeed material. At the discharge end of the screw there is a cone or likeconvex form of end plate whereby the press cake is discharged through anannular orifice surrounding the cone. Generally the pitch of the screwdiminishes toward the discharge end in order to enable application ofsumcient pressure to express the desired amount of water. Manydifficulties are encountered in the operation of such conventional screwpresses. In many instances it is difficult to provide for optimumfeeding of material to one end of the screw, with the result that thescrew is not operated at optimum capacity or with even loading. Due toinability to maintain the feed under optimum conditions there is afrequent tendency for the material under treatment to rotate about theaxis of the screw, which likewise results in decreased efficiency andcapacity, and requires the use of an excessive number of lock or plowbars. I

Aside from the difiiculties mentioned above conventional screw pressesare not applicable to-v the handling of materials of slurry or mush likeconsistency. Such materials cannot be properly advanced under pressureby a conventional screw operating at the speeds customarily used forsuch equipment. As a result it is customary in the treatment of suchslurries to first resort to supplemental dewatering methods, such assettlement or centrifugation, in order to provide a material dewateredto such an extent that it can. be supplied to the conventional screwpress equipment.

It is an object of the present invention to provide a screw press whichovercomes the difficulties outlined above. A particular feature of myconstruction is that it can be supplieddirectly with feed material ofslurry consistency.

A further object of the invention is to provide apparatusof the abovecharacter which operates at optimum capacity and efiiciency,particularly with respect to application of pressure and progression ofthe material undergoing treatment.

Another object of the invention is to provide an improved screw presshaving novel means for the mounting and adjustment of the end platecone.

Another object of the invention is to provide improved feed means forscrew press equipment in which centrifugal force is utilized to aid inthe elimination of liquor, whereby material of proper consistency issupplied to the feed end of a secondary screw press.

An additional object of the invention is to provide a primary screwpress in conjunction with a secondary screw press, andwhich primarypress is of novel construction adapted to receive feed material ofslurry consistency, and to supply properly dewatered feed to thesecondary press.

Additional objects of the invention will appear from the followingdescription in which the preferred embodiment of the invention has beenset forth in detail in conjunction with the accompanying drawing.

Referring to the drawing: I

Figure 1 is a side elevationalview, partly in section. illustratingscrew press equipment incorporating the present invention.

Figure 2 is an end view of the equipment illustrated in Figure 1.

Figure 3 is a cross sectional view taken along the line 3-3 of Figure 1.

Figure 4 is a side elevational detail in section showing the secondaryscrew and its associated parts but with the screen basket removed.

Figure 5 is a cross sectional view taken along the line 55 of Figure 1.

The screw press equipment illustrated in the drawing consists generallyof a suitable supporting frame It upon which are mounted the primary andsecondary press units It and I2. Feed material being supplied to theapparatus is introduced into the feed hopper l3, and dewatered presscake is discharged from one end of the secondary unit I2 (the right handend as viewed in Figure 1). The expressed liquid is collected bylaunders or pans underlying the units l I] and [2, as will be presentlydescribed, and'is finally withdrawn through the pipe I4.

The primary unit ll consists of a frame [5 which is mounted upon thebase H1, and which forms a feed hopper I1 adapted to receive materialfrom the lower end of hopper I3. A feed screw !8 is carried by the frame15, and is provided with a stub shaft I 9 extending from its one end.The shaft is carried by bearing 2| mounted on the frame [5, and by asecond bearing 22 carried, by the standard 23. Suitable drive means isapplied to shaft 19, such as the V belt pulleys 2 4, driven by V beltsfrom the electric motor 26.

That part of the screw l8 which extends beyond the frame It issurrounded by the two part screen basket 2?. As is conventional practiceeach part of the basket consists of the arcuate ribs 23 which areattached at their ends to the longitudinally extending bars 29. The ribsserve to support a suitable screen assembly 3| which is cylindrical inform and which surrounds the feed screw, in close apposition to theexterior end faces of the screw threads or flights.

The frame of the secondary unit, which has been designated generally at33, includes a chamber 34 having an opening 36 communicating with thedischarge end of basket 21. Chamber 34 is cylindrical as illustrated inFigure 5, and it is formed in two parts 37 and 38. Part 31 is of solidplate while part 38 is made perforated or as a screen. Part 38 comprisessubstantially onehalf of the walls of chamber 34, and particularly thathalf which is diametrically opposite from the opening 36.

The secondary screw press I2 consists of the screen basket whichsurrounds the horizontally extending feed screw 42.

As is customary practice basket M is formed of two halves clampedtogether, with each half consisting of the arcuate ribs 43, with theirends connected by the longitudinally extending bars 44. Bibs 43 serve tosupport a suitable screen assembly 56, whereby a substantiallycylindrical screen is disposed about the screw. In assembling thishasket, bars 44 are clamped by bolts 41 upon opposite sides of thelongitudinally extending bars 48, which form a part of the generalframe. It will be noted that the flights 49 on the screw have the samepitch throughout the length of the screw, and it is desirable that theybe interrupted at regular intervals, in order to accommodate thestationary lock bars These bars tend to prevent the general rotation ofthe material'being acted upon whereby the material is properly advancedas the screw rotates. One end portion of the screw 42, which forms thefeed portion of the same, extends into the chamber 34. The other ordischarge end of the screw extends in proximity to a ring 52 which iscarried by the frame, and which forms acircular opening in alignmentwith the screw and serving to accommodate the discharging press cake.

Adj ustably disposed within the opening formed by ring 52 there is acone 53, whereby the discharging material must pass through the annularorifices 54. A shaft 55 extends from the screw and is provided with athreaded portion 57. splined to the shaft 5%, whereby the cone rotateswith the screw, but may be adjusted in a longitudinal direction. A pairof nuts 59 and I5! are threaded upon the shaft 56 and are providedrespectively with a suitable handwheel 62 and handles 63, to enable themto be locked or disengaged with respect to each other. A tube 84 has itsone end attached to nut 59 and its other end provided with the collar66. A counter bore in this collar servies to accommodate a portion ofthe hub 58, and these parts are attached together for relative rotationas by means of screws 6'1 which are carried by the collar 66, and whichhave their inner ends extending into an annular ring 58 on the hub 58. Aspring 65 abuts against the outer face of hub 53 and is seated in anannular groove formed in the tube I34. Tube 84 is carried by a bearing69 which in turn is carried by the yoke I I. It will be evident thatwith the arrangement just described one may loosen the nuts 59 and BIwith respect to each other, after which one may turn the handwheel E2 toadjust the cone 53 in a longitudinal direction with respect to thescrew. When the cone has been located in a desired adjusted po- Cone 53is carried by a hub 58 which is effect of centrifugal force.

sitionthe two nuts 59 and SI are locked by jamming them together. Aspreviously mentioned the cone 53 rotates with the screw, as is also thecase with nuts 59 and BI. However while the parts are in rotation it ispossible for an operator to loosen and change the setting of the nuts.

The other end of the screw 42 is provided with a projecting shaft I2,which is accommodated within a suitable packing gland andbearing 73. Assuitable drive means for the screw 42, shaft '52 is shown carrying the Vpulleys M, which are engaged by V belts I6 leading from V pulleyscarried by the electric motor 77.

Extending beneath the screw 42 there is a suitable'pan or launder BIwhich is tilted for drainage of liquid to the pipe I4. A similar drainpan 82 extends beneath the screw I8, and discharges into the pan 8|.

Operation of the apparatus described above, in the carrying out of thepresent method can be described as follows: In a typical instance a feedmaterial is being treated containing from say 25 to 40%-solids. Thismaterial may for example be wine pomace such as is produced in the-wineindustry. Instead of driving the screw I8 at a rate of the order of from10 to 15 R. P. M., which would be common in the operation of ordinaryscrew presses, it is driven ata relatively high rate of speed, asforexample of the order of from to 400 R. P. M., where the screw has anoutside diameter of the orderv of 6 inches, and a pitch of the order offrom 3 to 6 inches. This provides a peripheral speed of the order offrom to 650 feet per minute. The sec-i ondary screw 42 however is drivenat a relatively low speed. Thus assuming that the secondary screw has adiameter of the order of. 15 inches, with a pitch of 6 inches, it can bedriven at speeds such as from 11 to 20 R. P. M. While the particularspeeds employed for driving the two screws will vary in practicedepending upon the material being handled, the diameters of the screws,the pitch of the flights, and like factors, in general it is desirablethat the primary screw I8 be driven at a speed many times the speed ofrotation of the secondary screw.

The feed slurry is supplied to the hopper I3 at a suflicient rate tomaintain this hopper partly filled. This causes complete flooding of thechamber I! at all times, whereby the screw I8- i at all times completelysubmerged in the material being treated. As the slurry is advanced alongthe screen 3| by the screw I8, a considerable amount of the water passesthrough the screen and is collected by the drain pan 82. By the time thematerial has progressed to the discharge end of the screw [8 its liquidcontent has been reduced to the point where it is of proper consistencyfor further treatment in the secondary unit I2. Thus assuming that thematerial contains from 25 to 40 percent solids at the time it issupplied to the hopper I3, upon reaching the discharge end .of the screwIB it may in a typical instance contain from 40 to 50 percent solids.

While being acted upon by the screw I8 water is expressed not onlybecause of the pressure being applied to the material, but in additionbecause of the pressure being applied due to the Centrifugal force isapplied in a direction tending to urge water outwardly .throughthescreen 3| because the materialbeing acted upon by the rapidly rotatingscrew rotates about the axis of the screw, although at a rotationalvelocity somewhat less than the rate ofrotation or the screw itself.Considerable static pressure-is appliedto the pulp beingdischargedthrough openingriifi, and this pressure serves toinsure-complete filling of the chamber 34, thereby preventingthe'formation of voids in the operation on the secondary unit [2. Boththepressure and the movement of the material through opening 36 carriesit completely around the adjacent end of the feed screw, and at thispoint some additional water is expressed from the material through thescreen 38. Secondary screw 42 causes progression of the material fromchamber 34 through the screen 46, with a gradual application ofincreasing pressure and with a further removal of water. By the time thesolids have reached the discharge end of the unit [2 the material maycontain, (taking wine pomace as an example) from 45 to percent solids.Such a material in the form of press cake is discharged through theannular orifice about the cone 53.

As is known to thoseskilled in construction and operation ofconventional screw presses, the setting of the cone 53 can be adjustedfor the purpose of adjusting the pressure applied to the material beingtreated, thereby securing a press cake of the desired moisture content.The fact that the cone 53 is mounted to rotate together with thesecondary screw minimizes the power requirements. In addition it ispossible to effect adjustment of the cone as previously described.

In general my equipment and method is applicable to treatment of avariety of feed materials in the form of slurries or which are ofmush-like consistency. Such materials cannot Y be supplied to anordinary screw press because they tend to rotate with the screw or inother words they will not hold, in the parlance of those skilled in theart. Treatment in my equipment serves to remove liquid from such feedmaterials by treatment with the primary screw, whereby when the materialis delivered to the secondary screw, it is of such consistency that itwill hold.

Although in the foregoing description particular reference has been madeto wine pomace, which consists of solids together with water, in manyinstances the liquor content may consist of an oil with or withoutwater. For example in the treatment of copra the feed material mayconsist of the ground copra fiber together with copra oil and water.Both oil and water are partially removed by treatment with the primaryscrew, and additional oil and water are removed by treatment with thesecondary screw. An example of another type or feed material is anindustrial pulp such as is found in solvent extraction processes, wherea fibrous material is mixed with liquid solvents such as petroleum,ether, alcohol, or carbontetrachloride.

It will be evident that the liquor content of the feed material suppliedto the equipment will vary in different instances and further more thatthe consistency of the feed material will vary not only in accordancewith the percentage of solids present, but also with the character ofthe liquor and the properties of the solids present. Such factors mustbe considered in operating my equipment, particularly with respect toremoving a sufficient amount of liquor by the primary screw whereby thematerial when delivered to the secondary screw will hold in the mannerdesired.

The elimination of an inner bearing for the primary feed screw I8 is adesirable feature of the machine. If it were attempted to utilize aninternal hearing at the discharge end of this screw the bearing wouldinterfere with proper movement of the material, and would tend to causeblocking. In effect this feature of the machine provides a floatingprimary press screw which is free to rotate without any restrictionother than the back pressure applied to it as the result of its actionupon the material being treated. The provision of the screen 38 is adesirable feature in that when handling feed materials containing arelatively high percentage of water or other liquids, a substantialamount of liquid is removed through the screen 38, thereby considerablyincreasing the effectiveness and capacity of the secondary screw.

It will be evident that my equipment can be modified in many respectswithin the spirit of the present invention. For example a double set ofthreads can be used on the screws in place of single threads or flightsas illustrated.

I claim:

1. In a press construction for the handling of a feed of slurryconsistency, a feed screw adapted to be rotated, a cylindrical shapedscreen surrounding the screw and providing a cylindrical space foraccommodating the screw, means for supplying slurry-like feed materialto one end of the screw whereby such material is advanced along thescrew with a part of its liquid content passing through the screen, asecond screw disposed at right angles to the first screw and having itsone end positioned to receive material from the discharge end of thefirst screw, a screen surrounding the second screw, means at thedischarge end of the second screw for enabling the discharge of presscake, the last named screen at the feed end of the second screw being insubstantially unobstructed communication with the discharge end of thefirst screen, and means for driving both the first and second screws,the rate of drive of the first screw being of the order of R. P. M. ormore for a screw 6 inches in diameter and having a pitch of from 3 to 6inches, and the rate of drive for the second screw being relatively slowcompared to the first screw, whereby centrifugal force aids delivery ofliquid through the screen surrounding the first screw while the secondscrew removes liquid by compression.

2. In a press construction for the handling of a feed of slurryconsistency, a feed screw adapted to be rapidly rotated, a substantiallycylindrical shaped screen surrounding the screw, a basket serving tosupport said screen, said screen and basket forming a substantiallycylindrical space for accommodating the screw, means for supplying feedmaterial to one end of the screw whereby such material is advanced alongthe screw with a part of its liquid content passing through the screendue to the combined pressing action of the screw and centrifugal forceresulting from rotation, a second screw disposed at right angles to thefirst screw, one end of the second screw being disposed to receivematerial from the discharge end of the first screw, a substantiallycylindrical shaped screen surrounding the second screw, a second basketserving to mount the second screen, said second basket and screw havingsubstantially unobstructed communication with the discharge end of thefirst basket and screen, means at the discharge end of the second screwfor enabling the discharge of press cake, and means for driving saidscrews, the rate of drive of the first screw being of the order of 90 R.P. M. or more for a screw having a diameter of 6 inches and a pitch offrom 3 to 6 inches, and the rate of drive of the second screw being ofthe order of 20 R. P. M. or less for a screw having a diameter of 15inches and a pitch of 6 inches.

CARL A. RIETZ.

REFERENCES CITED The following references are of record in the file ofthis patent:

Number 8 UNITED STATES PATENTS Name 7 Date Westhafer June 9, 1925 LangMar. 29, 1932 I-Iiller Mar. '7, 1939 Anderson July 22, 1941 AndersonMar. 3, 1942 Rietz July 27, 1943 Meakin Jan, 25, 1944

